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APPARATUS DEVELOPED TO SIMPLIFY MANUFACTURE OF LENS WHEELS FOR CONTINUOUS PROJECTORS
ARTHUR J. HOLM AN*
The continuous projector described briefly in Volume XII, Number 36, of the Transactions under the classification, "Symposium on New Motion Picture Apparatus," is essentially a precise optical instrument requiring a higher degree of accuracy in manufacture than is customary in optical work. The lens wheels, shown in position in the mechanism (Fig. 1), are the essential and characteristic elements of this projector. In order that the screen image may possess the critical definition and the steadiness essential to good projection and may also have, to the fullest extent, the peculiarly pleasing qualities this system of projection is capable of producing, it is essential that the lens wheels be accurate.
The optical accuracy of the lens wheels depends principally on three factors: first, the accuracy of curvature of surfaces of each lens sector; second, the exactness of matching of all lens sectors on the lens wheel; and third, the exactness of positioning of optical centers of lens sectors in the final lens wheel assembly. The first requirement calls for the best product of a first class optical shop. The second requirement presents to such a first class shop a restriction never before imposed in quantity production, for these lens sectors must be "matched" in the highest sense of the word. The third requirement is entirely new to the optical industry and involves a new and precise method of centering and indexing.
With these problems standing in the way of commercial manufacture, it is not at all surprising that those skilled in the arts of projection and lens making have hitherto considered this projector impossible from a practical standpoint although they are willing to admit that exceptionally pleasing screen results are obtained with a perfected machine. The inventions described herein have entirely solved these difficulties of manufacture and will, I trust, be of interest to the members of our Society, especially in view of the fact that we are about to
* 59 Auburn St., Brookline, Mass.
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